20 



Fig. 24 is drawn from the cortex of a Western variety of Ch. 

 aspera, showing at " 1' ' a lateral cell filling out the whole space 

 between the two central internodal cells (primary cells) of the cortex. 

 In a section through "1"' less than the triple number of cells would 

 be seen. 



In the development of the node of the cortex, the growth of the 

 lateral cells may be entirely arrested, and these cells may remain in 

 the node undeveloped, or they may grow into spines (Ch. crinita), or 

 may variously develop, as will be shown presently. 



-f 



I 



Fig- 25. 



Fig. 26. 



In case the nodes do not develop lateral cells lying pressed against 

 the stem as cortex cells, then only the primary cells of the cortex 

 system are found ; we see as many cortex cells as there are leaves, 

 and the stem is said to be " haplistocha corticata " (singly corticated). 

 This is seen in our Ch. crinita, two cortex tubes of which are repre- 

 sented in Fig. 25. These primary cells approximate each other 

 closely and completely encircle the stem, forming a single cortica- 

 tion. The nodal cells develop spines, three usually, at each node, but 

 no lateral cortex tubes. 



